The invention relates to a method of producing optical polymer components having integrated vertical coupling structures, wherein the optical polymer components have regions for receiving light waveguides and fiber guide structures, preferably configured as V-shaped positioning trenches, for receiving optical fiber structures to be coupled to the light waveguides, and the polymer components comprise a polymer substrate and a polymer lid plate. More particularly, the present invention relates to a method of producing optical polymer components, as mentioned above, having integrated vertical coupling structures, and which is used in the mass-production of monomode or multimode components, particularly opto-optical components, of integrated optics having monolithically-integrated fiber-chip coupling.
The increasing use of integrated-optical components for optical communications, for sensory technology and the computer field (optical databus) lends ever-increasing significance to optical connection techniques (chip-fiber coupling) and optical coupling techniques. Smaller, private relay stations having approximately 1000 subscriber stations already require, for example, several thousand optical connections and coupling stations between the individual sub-switching stages, because the number and complexity of the optical components integrated on individual substrates are severely limited due to the extreme aspect conditions in the optics. In such cases the reliability (mechanic and thermal stability) and ability of the optical connection and coupling technology to be realized, and the required connection expenditure ultimately determine the achievable degree of expansion of an optical relay system.
The basic mode of operation of vertical directional couplers is known in which two light waveguides disposed one above the other approach one another so closely over a defined length that a coupling occurs between them and energy can be exchanged. Usually such components are structured in stacked, thin films (film waveguides), with the layer lying between the waveguides determining the coupling strength of the waveguides with its optical thickness. The homogeneity of this intermediate layer is therefore critical for the operation of such components, and technologically difficult to control. Moreover, up to now neither self-adjusting optical connection techniques for such waveguides located at different heights, nor mass-producibilty of such components using an injection-molding technique has been possible.
In known parallel strip couplers, typically coplanar waveguides must be guided precisely adjacently in the coupling region with a few .mu.m lateral spacing over a few hundred .mu.m coupling length. Such structures are difficult to realize using injection-molding techniques, because very narrow webs for the waveguides would have to be produced between trench structures.
So-called imprinting techniques for monomode light waveguides in plastics ("embossing" or photopolymerization) are known from H. Hosokawa et al in the Integrated Photonics Research Conf., (1991). However, neither an arrangement of waveguides one above the other nor the simultaneous production of a substrate-integrated fiber guidance is possible in this technique.
Furthermore, it is known from A. Neyer et al in the Integrated Photonics Research Conf., (1992) to shape waveguide structures in a substrate and then fill this with a light-guiding polymer having a high refractive index. In this instance waveguides can only be created on one side in a substrate layer, but an arrangement of waveguide coupling structures one above the other is excluded.
Moreover, the principle of duplicating microstructures using galvanic shaping and injection-molding is known as the so-called "LIGA" technique. In this technique the primary structures to be shaped are usually created by means of X-irradiation of plastics on a synchrotron, and from there the mold inserts for the injection molding are galvanically produced. An alternating arrangement of higher-lying and lower-lying fiber guide structures, as become necessary for vertical coupling elements, is not possible according to the current state of the LIGA technology, because the necessary X-irradiation principally permits no depth resolution.